Implantable leads are used in conjunction with many different types of therapeutic medical devices, such as pacemakers, cardioverters, cardiac defibrillators, neural stimulators, and the like. It is generally deemed desirable to secure an implantable lead in some manner so that proper positioning and placement of the lead is not disturbed. In the past, various techniques and mechanisms have been proposed for securing implanted or partially implanted leads in a patient. When transvenous leads were first introduced in the 1970's, physicians often employed a "butterfly-type" anchoring sleeve provided with the lead. The anchoring sleeve, attached to the lead body during implantation, provided a structure adapted to be sutured to a vein or underlying tissue, and further protected the lead insulation from the stress of having a suture tied around it.
When polyurethane leads were introduced in the late 1970's, they were frequently provided with a prefitted sleeve to facilitate the securing the lead with sutures. Such sleeves were particularly advantageous for polyurethane leads, which tended to have thinner insulation layers than earlier leads. The sleeves were typically silicone rubber, and adapted to slide along the lead body. In operation, the physician would slide the sleeve to a position near where the lead enters the vein, and suture the sleeve to the vein or to underlying tissue to secure the lead.
Several examples of prior art suture sleeves are known in the prior art, including those disclosed in U.S. Pat. No. 4,516,584 issued on May 14, 1985 to Garcia entitled "Suture Collar" (cylindrical collar with longitudinal bore); U.S. Pat. No. 4,553,961 issued on Nov. 19, 1985 to Pohndorf et al. entitled "Suture Sleeve with Structure for Enhancing Pacing Lead Gripping" (cylindrical collar with longitudinal bore containing structure for enhancing gripping between collar and lead); U.S. Pat. No. 4,672,979 issued on Jun. 16, 1987 to Pohndorf entitled "Suture Sleeve Assembly" (tubular sleeve and collet member adapted to snap together); U.S. Pat. No. 4,683,895 issued on Aug. 4, 1987 to Pohndorf entitled "Suture Sleeve Anchoring Device" (circular staple-like clip for attaching a suture sleeve to tissue); U.S. Pat. No. 5,107,856 issued on Apr. 28, 1992 to Kristiansen et al. entitled "Multiple Lead Suture Sleeve" (generally "W"-shaped sleeve adapted to be compressed by sutures around one or two leads); and U.S. Pat. No. 5,129,405 issued to Milijasevic et al. on Jul. 14, 1992 entitled "Vein Suture Collar" (cylindrical collar with longitudinal bore).
Other tubular member securing mechanisms have been proposed in the prior art. Earlier examples include U.S. Pat. No. 3,176,690 issued on Apr. 6, 1965 to H'Doubler entitled "Catheter Having Integral, Polymeric Flanges" (elongated external flange integrally formed in the catheter body); U.S. Pat. No. 3,730,187 issued on May 1, 1973 to Reynolds (securing collar permanently located on the outer surface of the catheter and having a dacron suture embedded therein); and U.S. Pat. No. 3,724,467 issued on Apr. 3, 1973 to Avery et al. entitled "Electrode Implant for the Neuro-Stimulation of the Spinal Cord" (physiologically inert plastic tie-down clamp); which described various types of collars or tabs attached to the tubular member for providing a suturing structure.
Still other types of lead or catheter securing devices are disclosed, for example, in U.S. Pat. No. 3,821,957 issued on Jul. 2, 1974 to Riley et al. entitled "Retention Slide for Catheters and Other Tubular Materials" (retention slide having tubular portion and four flexible, radially projecting tabs); U.S. Pat. No. 3,880,169 to Starr et al. on Apr. 29, 1975 entitled "Controlled Entry Pacemaker Electrode for Myocardial Implantation" (rectangular sewing pad adhesively bonded near distal end of lead and providing wings for suturing); U.S. Pat. No. 4,266,552 issued to Dutcher et al. on May 12, 1981 to Dutcher et al. entitled "Lead Anchoring Bobbin" (silicone rubber bobbin for receiving a looped portion of the lead); U.S. Pat. No. 4,276,882 issued on Jul. 7, 1981 to Dickhaudt et al. entitled "Lead Anchoring Device" (two-piece disc-shaped device for clamping one or more leads therebetween); and U.S. Pat. No. 4,287,891 issued on Sep. 8, 1981 to Peters entitled "Securing Device" (two-piece cylindrical device with longitudinal bore which grips tubular member when twisted).
The present inventor believes that known silicone rubber suture sleeves have several disadvantages. Sleeves which must be placed on the lead during manufacture can only be removed by cutting them off, as with a scalper, when physicians do not wish to use them. This is considered undesirable, since there is a risk that the insulation of the lead would be damaged while the sleeve was being cut off.
Moreover, it has been the inventor's experience that when a silicone rubber suture sleeve becomes wet or infiltrated by moisture, the friction between the lumen of the sleeve and the lead may be reduced so much that the lead is allowed to slide, and is no longer anchored in place.